What a Shed Slab Actually Needs (and What Moves the Price)

A shed slab in Gippsland is not just a thinner house slab. What moves the price is the thickness you actually need, whether the shed kit comes with its own footing spec, how far the truck and the pump can get in, and what the ground does when it gets wet.

People ring up expecting the shed slab to be the cheap version of a house slab. Sometimes it is. Often it isn't, and the reason usually turns up in the kit paperwork rather than anything I've done to the quote.

The shed kit decides more than you'd think

Nearly every shed kit comes with an engineer's footing detail. It tells you how thick the edges have to be, where the tie-down points sit, and what reinforcement goes in. That drawing is not a suggestion. The shed supplier's warranty and your building permit both lean on it.

So the first thing I ask for is that drawing. If you've got it, I can price the job properly. If you haven't ordered the shed yet, I can give you a range, but the number firms up once the spec exists.

Thickness follows what you'll actually do in there

This is where people either overspend or, more often, underspend and regret it.

• Storage and a mower: a standard domestic slab thickness is usually fine
• A workshop with a bench, a welder and a car in and out: worth going thicker through the middle
• A hoist, a truck, a tractor or a loaded trailer parked on it: this is a different slab, with thicker sections and more steel, and it needs to be designed that way from the start

The trap is putting a hoist in two years after the pour. Retrofitting a hoist into a slab that was never built for it means cutting out and repouring a section, and that costs more than doing it right the first time would have. If a hoist is even a maybe, tell me at the site visit.

Reactive clay, and why prep is not the place to save

Plenty of blocks around Sale and through the Wellington Shire flats sit on reactive clay. Reactive ground swells when it's wet and shrinks when it dries, and it does that every year. A slab sitting on it without the right prep and the right steel will move, and once it moves it cracks.

So a decent shed slab has proper excavation, compacted fill in layers, and the reinforcement the engineer asked for. That work is invisible the day the shed goes up. It's also the part that decides whether the slab is still flat in fifteen years.

If a quote is a long way under the others, this is usually where the difference is hiding.

Access is a real cost, not a technicality

Sheds tend to go up the back of the block, behind the house, past the fence. That's exactly where a concrete truck can't reach.

• If the truck can back up to the formwork, that's the simplest and lowest cost setup
• If we need a pump, that's a fixed cost on the day plus a rate for the run
• A long pump line over a house adds time and hands, and both go on the quote
• Soft ground in a Gippsland winter can stop a loaded truck getting in at all, which sometimes means waiting for a dry week

None of that is padding. It's the difference between three people and a straightforward pour, and five people and a pump booking.

Falls and drainage, so the shed stays dry

A shed slab wants a slight fall so water runs out rather than sitting against the frame. Get this wrong and you get a puddle inside the roller door every time it rains hard, which is a thing you cannot fix afterwards without grinding or repouring.

We set the falls at the site visit, looking at where the water already goes on your block. That's another reason I'd rather stand on the ground than quote off a phone call.

Do you need a permit?

Usually the slab rides on the shed's building permit rather than needing one of its own. That permit is the owner's or the builder's to lodge, not the concreter's. I'll pour to the approved detail and I'll tell you if what's drawn doesn't match what's on the ground, but the approval itself sits with you.

Check with your council before you book a pour date. Wellington Shire, Latrobe City and East Gippsland Shire all handle it slightly differently.

So what does it cost?

I'm not going to put a per square metre number on this page, because the honest answer is that the same size shed slab can vary a long way on two blocks a street apart. The ground, the footing spec, the access and the fall do the moving.

What I will do is come and look, measure it, and put a written quote in front of you with the prep and the steel itemised so you can compare it properly against anyone else's. If someone gives you a confident price over the phone without seeing the block, they've either padded it or they're going to find a variation halfway through.

Book a proper site visit and we'll work out what your shed actually needs. Or call me on +61 400 345 453.